JavaDoc for everything (almost), and TaskTags

I added JavaDoc-Comments to nearly any class and method.
Exceptions: Everything in fineDrinks.client.* . I had no idea how to
comment that, I leave that to Matjer.

Also, you might now find the following Eclipse-TaskTags in the Code. To
find them via the TaskView, you have to add them manually. Feel free to
add your own. It is not necessary to add them, but it will might improve
teamwork. Feel free to ask about any tag if you are unsure why it
exists.
These TaskTags are currently in use (some are predefined):
<name>            <priority>
FIXME                 High
INFO                   Low
QUESTION         Normal
TODO                 Normal
UPDATE_DOC   Low
UPDATE_DOC_URGENT   High
XXX                     Normal